Why not just make the case separable? Seems to me a lot easier this way
[tex] y^2+y - x y^{\prime} = 0 \Rightarrow \frac{y^{\prime}}{y^2+y}=\frac{1}{x} \Rightarrow \frac{dy}{y^2+y} = \frac{dx}{x} [/tex]
and this is an easy integral to do.

Note that usually, non-linear diff.eqs rarely can be solved by methods of finding integrating factors.
That is, the method of finding an integrating factor is mainly of use for solving linear diff. eqs.